Atherosclerosis (AS) is a common cardiovascular disease with high morbidity and mortality globally. Circular RNAs (circRNAs) have been shown to regulate AS progression. However, the biological role of circ_0,003,423 in AS pathology and its associated mechanism is still unclear.

Oxidized low-density lipoprotein (ox-LDL)–induced human umbilical vein endothelial cells (HUVECs) were used as an AS cell model in vitro. Reverse transcription–quantitative polymerase chain reaction (RT-qPCR) and Western blot assays were conducted to measure ribonucleic acid (RNA) and protein expression. Cell proliferation was analyzed by Cell Counting Kit-8 (CCK-8) and 5-ethynyl-2′-deoxyuridine (EdU) incorporation assays. Cell apoptosis, migration, and angiogenesis were analyzed by flow cytometry, wound healing, and Matrigel tube formation assays. The oxidative stress factors were detected using reactive oxygen species activity (ROS) assay kit, malondialdehyde (MDA) assay kit, and superoxide dismutase (SOD) assay kit. The interaction between microRNA-142-3p (miR-142-3p) and circ_0,003,423 or sirtuin 3 (SIRT3) was verified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay.

Ox-LDL exposure dose-dependently reduced circ_0,003,423 expression in HUVECs. Ox-LDL suppressed the proliferation, migration, and angiogenesis and induced the apoptosis and oxidative stress of HUVECs, which were offset by circ_0,003,423 overexpression. miR-142-3p is a direct target of circ_0,003,423, and circ_0,003,423 overexpression-mediated protective effects in ox-LDL–induced HUVECs were largely reversed by the addition of miR-142-3p mimic. miR-142-3p directly interacted with the 3′UTR of SIRT3 and SIRT3 knockdown reversed anti-miR-142-3p-mediated protective effects in HUVECs upon ox-LDL exposure. Circ_0,003,423 positively regulated SIRT3 expression by sponging miR-142-3p in HUVECs. In addition, circ_0,003,423 could regulate the SIRT3/SOD2 signaling pathway in HUVECs.

Circ_0,003,423 protected HUVECs from ox-LDL–induced dysfunction by sponging miR-142-3p and activating SIRT3/SOD2 signaling, which provided new potential targets for AS intervention and treatment.